1. Field of the Invention
The present invention relates to a bag provided with a gas filling compartment for enhancing the shape retention and autonomy of the bag and protecting the contents packaged from shock or the like and more particularly to a method for sealing a gas into the gas filling compartment and further to a packaging method comprising for bag having a gas filling compartment that includes a process for sealing a gas into a gas filling compartment.
2. Description of the Related Art
A self-standing bag (standing pouch) is a bag that exhibits enhanced self-standing properties, innovations having been made in the shape of the bottom surface or the shapes of the bottom surface and the side surfaces thereof. Bottom-gusseted type self-standing bags manufactured such that another folded film (bottom member) is sandwiched in the bottom part of the front and back films (trunk member), and the two lateral side edge parts and bottom edge part are heat-sealed, are widely used. Self-standing bag products that are filled with contents and have the bag mouth sealed can be used in displays or on tables, and the use thereof as a resource-conserving packaging material replacing rigid containers is expanding.
With these bottom-gusseted type self-standing bags; however, when they are large in size or have a spout or the like attached at the bag mouth part, the bag will be too flexible, and problems will arise. The upper part thereof bends over when the bag is displayed or used on a table, the appearance thereof deteriorates, or the self-standing properties thereof are lost so that it topples over. Other problems are that it will be difficult to pour contents from the self-standing bag, because the bag readily bends over, and the bag will be difficult to hold. As to the latter problem, the same thing can be said about flat bags and the like in general.
For such reasons, in Japanese Design Registration Nos. 1247027 and 1247514, for example, an unbonded part is formed in the bag outside of the contents storing section, or, more specifically, an unbonded part is formed (so as to be a gas filling compartment or air bag) in the lateral side edge sealed portion, a gas is sealed therein, and the shape retention of the bag, and handling properties when the seal is opened, are enhanced.
Meanwhile, bags comprising an inner bag and an outer bag, having a gas sealed between the inner bag and the outer bag (gas filling compartment) to protect the packaged contents accommodated inside the inner bag from shock or the like, are described in Japanese Patent Application Laid-Open (Kokai) 64-84869, 2-98563 and 9-132213 and also in Japanese Utility Model Application Laid-Open (Kokai) No. 8-1398.
However, the methods for sealing gas into the gas filling compartment which are disclosed in the related art cited above are not suitable for automation, and it has not been possible to adopt such as a part of an automated packaging operation process wherein a commonly known automated packaging apparatus such as a rotary type packaging apparatus is used.